MXPA97008198A - Addition method of a retention aid program for improved car production - Google Patents

Abstract

The present invention relates to a method for manufacturing cardboard which does not contain filler or inorganic filler. The fine pulp particles from the waste water system and retention agents are mixed and then fed to the countercurrent material of the papermaking machine prior to mixing with the long fiber material. Once the flocculation occurs, the material is drained to form a sheet and the sheet is

Description

"METHOD OF ADDICTION OF A RETENTION AID PROGRAM FOR IMPROVED CARDBOARD PRODUCTION" FIELD OF THE INVENTION The present invention relates to a method for making paper, and more particularly, to a method of making cardboard.

BACKGROUND OF THE INVENTION European Patent Specification Publication No. 0 041 056 teaches a papermaking method in which inorganic filler, colloidal silica and cationic starch are added to an aqueous suspension of cellulose fibers upstream of the inlet to the machine paper manufacturer for the purpose of increasing the strength of the paper and improving the retention of filler or filler in the wire mesh belt. Swedish Patent Application 850016206 teaches a papermaking method in which an aqueous suspension of a filler or inorganic filler is first mixed with fine particles of pulp, subsequently a Ref .: 25970 retention agent is added (cofloculation) and the flocs thus formed are introduced into the pulp suspension at a countercurrent location of the papermaking machine whereby the retention of the filler or filler is improved and improve the properties of the paper. U.S. Patent No. 4,889,594, published by Gavelin, teaches the use of an apparatus attached to a papermaking machine for use in the coflocculation of filler or filler and fine pulp. Although the method taught by EP 0 041 056 provides a very good result, it has the disadvantage of requiring the use of large quantities of expensive starch and is very difficult to apply in practice due to the complexity of the added ingredients and their reactions with substances locally incidental. Therefore, results may vary from plant to plant. The method according to Swedish Patent Application 8500162-6, although it presents a very simple or pure solution, still causes problems in achieving a result which can be reproduced in practice. It has been found that the resulting flocs or fillers and fine pulp break or spoil to some extent prior to being loaded into the pulp suspension, resulting in damaged retention and requiring careful control of flocculation and degradation in a particular manner and with the help of a special device to achieve the desired result. U.S. Patent No. 4,889,594, published by Gavelin, teaches the use of an apparatus attached to a papermaking machine to provide a suitable environment for mixing a retention agent and filler or inorganic filler for use in the manufacture of papers thin. These patents address the problem of loss of strength when the level of filler or inorganic filler is increased. Many compositions and applications that are useful in the manufacture of thin paper are unsuitable for use in the manufacture of cardboard. Several factors contribute to this incompatibility. Traditionally, the retention aid is not used in the manufacture of paperboard since the retention aid tends to damage the formation when it is added to complete or integral raw materials. This is because the cardboard uses the longer fiber to achieve increased strength and the longer fiber is more susceptible to flocculation leading to loss of formation.

Poor training causes loss of strength and poor or deficient leaf dehydration. Secondly, the manufacture of cardboard does not incorporate the use of any fillers since the fiber does not whiten and does not require the brilliance driven by the addition of fillers. The use of fillers or fillers could, in effect, impair the overall strength of the board, which is its most important property of the sheet. Since cardboard is designed primarily for strength, the use of a filler may not be appropriate. Therefore, it is an object of this invention to provide an improved method of flocculation of fine particles in the manufacture of paperboard.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing cardboard, which contains filler or non-inorganic filler. Fine particles of pulp from the wastewater or white water system of the papermaking machine are mixed with one or more retention agents and then fed to the upstream material of the papermaking machine. This introduces the fine particulate / pre-brazing retention mixture with the material or wood pulp ready to manufacture long-fiber paper. Once the flocculation occurs, the material or wood pulp ready to manufacture paper is drained to form a sheet and the sheet is dried.

DESCRIPTION OF THE PREFERRED MODALITIES When the process of the invention is carried out, the fine pulp is flocculated with the aid or assistance of one or more retention agents, before the pulp is introduced into the long fiber material fed to the papermaking machine. These result in the flocculation of fine particles without flocculation of the long fiber with loss resulting from formation. The retention agents suitable for use in accordance with the present invention are any of the typical retention agents used in papermaking, including high molecular weight polymers which provide an irreversible bridge formation between particles. Anionic, cationic and nonionic polymers can be used here. In order to effectively load the polymer into the system and obtain effective flocculation, it is necessary for each polymer molecule to come into contact with the largest possible number of particles. When flocculated according to the invention, the flocculation is carried out in the presence of a small proportion of the raw material of the total upper box and when the flocs come to be contacted with the long fiber material or pulp, at a later stage , the retention agent has already reacted and, to a large extent, joins active groups in the fine pulp. The retention of the flocs in the cardboard is caused by two mutual reaction reaction processes. According to the first of these processes, the floccules are separated or eliminated by filtration and are joined or held in the meshes of the fiber network in those places in which they are located when the fiber network is consolidated during the process of Dehydration of the pulp or material on the endless belt of the paper machine. According to the second of these processes, which is applied when using a cationic retention agent, the cationic flocs are attracted to the anionic fiber substances in the fibrous or fiber network, which amplifies the filtration process and contributes to the uniform distribution of the flocs in the direction of the Z axis of the paper. The method according to the invention is not dependent on the use of any particular kind of retention agent. The choice of the retention agent depends on those requirements established in the process and on the quality of the paper. A few retention agents which can be used in accordance with the invention are provided below. Flocculants such as acrylamide copolymers with cationic or anionic monomers, which can be obtained at various molecular weights and degrees of substitution. Coagulants, including DADMACs, epi-DMAs, condensation products of ethylene dichloride and amides, polyethylene imine, modified polyethylene amines and polyamide amines. These coagulants can be used alone or in conjunction with flocculants in double polymer programs. Nonionic flocculants such as polyacrylamide and polyethylene oxide. Both can be used with an intensifier such as phenol formaldehyde resins. Cationic starch can be used in the material or pulp to increase the dry strength of the paper or reduce the Z potential of the system and cause coagulation of the fine fraction or fine particle fraction. Other polymers of the polyamide type, polyamideamine condensate, cationic polystyrene latex, and inorganic compounds of the alum, polyaluminium chloride, and sodium aluminate type can also be used as retention agents according to the present invention. It is also possible, when practicing the invention, to use combinations of different retention agents, for example, two-component system or three-component systems. For example, a cationic retention agent can be combined with an anionic agent, in this case the cationic agent is preferably prior to the addition of the anionic agent. A microparticle can also be added to any of the single or double polymer programs described above. Commonly the particles in use include colloidal silica, bentonite, other smectite clays and anionic latex polymers. Suitable three-component systems for use in accordance with the invention are the combination cationic starch / anionic polyacrylamide / cationic polyacrylamide and the combination bentonite or colloidal silica / anionic polymer / cationic polymer. Suitable addition points for adding the retention aid according to the invention are any locations of the papermaking machine that contain only fine particles, for example, the tray or reservoir, pour water silo and branch or suction side of the ventilation pump. Preferably, the addition occurs at a point where at least a low level of turbulence occurs, for example, the side or suction branch of the ventilation pump. Numerous advantages are realized as a result of using the method of the invention. The main advantage is the increase in retention that occurs without a loss of dehydration, while the ability to function and the tensile strength / breaking of the final product increases. These benefits can not be achieved by adding the retention aid to the complete or integrated raw material (finer particles of long-fiber pulp) because the flocculation of long fibers will lead to loss in formation, with loss resulting in dehydration , aptitude to function and resistance. A second advantage is the reduced amount of retention aid that is required for use throughout the system of the papermaking machine. This reduction is done because the long fiber is not hot, when it is used for paper fibers used in the production of finer paper levels.

The following examples are presented to describe the preferred embodiments and utilities of the invention and do not mean limiting the invention unless otherwise stated in the claims appended thereto.

EXAMPLE 1 The effect of adding Nalco® 7523, a cationic flocculant of low charge density (0.14 meq / g), was measured in a cardboard manufacturing facility that manufactured the corrugated medium of the semi-chemical pulp. The 7523 was fed to the material or pulp of the endless belt (only fine particles) and compared with the premalla (conventional method - complete raw material). Although the addition of Nalco® 7523 in a conventional manner to the total raw material is beneficial, the interruptions of the total wet end reduced with the addition of material or pulp of the endless belt by 59.2% (from an average of 9.7 interruptions / day drops to 3.9 interruptions / day). The wet end interruptions, total, reflect both the texture interruptions (metallic endless belt) and the pressure section. On average, texture interruptions were reduced to ~ 72% when Nalco® 7523 was run through the material or pulp of the endless belt in the paper machine. Similarly, the level of interruption in the pressure section (Ia and 2a presses) was reduced to ~ 42% when the polymer was fed to the papermaking machine in the material of the metal endless belt. The lost time that results from all the interruptions of the wet part is reduced by ~ 58% when comparing the periods in which the polymer was fed into the material or pulp of the endless belt against those times or periods when he himself was fed to the premalla. The average of total minutes lost, when combining all the material or pulp of the endless belt against feeding evaluation periods with the premalla, was 70.3 minutes / day with the normal polymer fed and 29.9 minutes / day with the polymer of the material or pulp of the auger fed. This represents a net gain in production time of 40.4 minutes / day or 0.675 hours / day. Using a production speed of 15.66 TPH, there is an increase in daily production of 10.54 Tons per Day @ 100% operational efficiency). During the evaluation periods of Nalco 7523, the data suggest that the use of the current in the papermaking machine was reduced by ~ 5% when the polymer was fed into the material or pulp of the endless belt. As a result, the retention levels of the first step (during average production # 26) are increased from an average range of 70% -72% to an average range of 79% - 81% with polymer added in the material of the belt endless. This seems to be a significant improvement in the operation of the polymer by changing the feeding point to the branch or side of the material or pulp of the endless belt (only fine particles) in relation to the premalla (complete or complete raw material). In many cases, the polymer is fed to the essentially "preflocculating" white waters before the fine particles are driven back from the upper case. By targeting the polymer in the solids of the tray water that are initially only recirculated, this leads to a very high initial dosage of chemicals in the fine particles which are difficult to retain and which have the most damaging impact on the drainage of the paper making machine (due to its relatively high surface area and water storage or retention capacity). More importantly, improvements in retention and drainage are provided, without potentially compromising leaf formation. Maintaining good training means that voids in the forming or training area will remain at higher effective levels (less light and heavy areas where the integrity of the vacuum can be lost), transmitting a more uniform sheet of greater consistency and resistant to the wet network in the press section or the press. This can mean less opportunity for paper repellency in the press, very few interruptions of the wet part, and better opportunity for wet presses or to remove water and internal resistance of the shaped sheet.

Example 2 The draining and drying effects of Nalco® 7523 were measured in the carton making machinery. The effects of the polymer on the coil or reel humidity, current pressure, voids of the flat box or platform, and speed of the coil or reel were calculated. The differences were then measured before, during, and after this evaluation in average CFCO tests that take into account large weights # 33, average machine speeds, and average tons / hour. Nalco 7523 was added to the side or trailing side of the auger pulp at a target addition rate of 2 lb / ton. Three days later, the flocculant Nalco 7523 was removed from the papermaking machine system at least in the same, if not slower, speed that was taken during previous evaluations. Some of the observations made during this time period where the feed rate was reduced from 2 lb / ton to 0 lb / ton are as follows. The effect of reduced polymer dosages on the moisture levels in the coil was measured. Before each reduction of the subsequent polymer dosage, the humidity of the coil or reel was allowed to stabilize at less than 8.8% via increase in the current pressure of sections 4a and 5a, it was changed in the increase shoe abrupt to reduce the amount of water that is transported down the table, the dilution water is reduced, or through reductions in the speed of the machine, before the feed rate is further reduced. The coil humidities were 8.2% at a supply or dosage of 2 lb / ton and were raised to a maximum moisture level of 13.3% when the polymer was completely removed from the addition to the pulp of the endless belt. Prior to the decrease in polymer supply (ie 2 lb / ton), the current pressure was ~ 43 pounds / in. During processing the final reduction in dosage of 0.5 lb / ton falls to 0 lb / ton, the current pressure reaches a maximum level of ~ 94 lb / in2. The current of the third section increases slightly from ~ 112 pounds / in2 to ~ 116 pounds / in2, during the entire polymer removal of the papermaking machine. A decrease in the drainage of the endless belt was observed after removal of the retention aid and drained on the endless belt. This decrease in the drainage of the belt or belt was shown by the significant increase in the level of vacuum of the platform or flat box # 3. At the 2 lb / ton dosage, the vacuum of the flat box # 3 was ~ 7.35"Hg. This was increased by -27% to a vacuum reading of 9.3" Hg when the polymer had come out completely. This increase remains at this elevated level even after the machine tends to be compensated through reductions in drag to slower drag (-60 fpm to -70 fpm) and machine speed. The position of the moisture line taken to ~ 3 feet further descends the machine (towards the pressure or press section) when the dosage or supply of 2 lb / ton is compared to the addition without polymer. In addition, the 2-sigma moisture profile of CD moisture was much poorer after polymer removal (1.30% @ 2 lb / ton versus 1.85% + @ 0 lb / ton). As for the speed of the machine, at the dosage or supply of 21b / ton, the machine was operated at the coil speed of 1,370 fpm (feet per minute). Once the polymer had been completely removed, the speed of the coil had been reduced below 1.355 fpm for an effective reduction in speed of 15 fpm (while operating at significantly higher current pressures). The CFCO test averages of the pretest, test and post-test periods during the operation of greater weight # 33 were the following: * Pretest 74.4 pounds / in2 Test with Nalco 7523 77.2 pounds / in2 * Post test 72.8 pounds / in2 The average speeds of the machine during the pre-test, test, and post-test periods during the evaluation of the Nalco® 7523 polymer while working with medium # 33 were as follows: * Pre-test 1449 fpm (feet / min) Test with Nalco 7523 1461 fpm (feet / min) Possay 1442 fpm (feet / min) Production speeds (tons / hour) when comparing the pre-test, trial and post-test periods are as follows: Pretest 15.72 tons / hour * Test with Nalco 7523 17.22 tons / hr * Post-test 16.09 tonnes / hr In summary, when comparing the effects of a polymer feed or feed rate of 2 lb / t without addition of polymer, the following observations are documented. To achieve the same polymer-free coil moisture levels, approximately 41 psi of the dryer's current pressure of the additional sections 4a and 5a were required (~ 43 lb / in2 @ 2 lb / ton versus 84 lbs / ft2 @ 0 lb / ton). Additionally, a reduction in machine speed of 15 feet per minute (fpm) was also necessary due to the draining of the most impoverished tape or band and poorer moisture profiles / higher humidity. It was also necessary to reduce the faster drag from -60 feet per minute to -75 feet per minute while reducing the position of the 78% dilution valve to 69%.

Example 3 TABLE 1 All this lamination, cardboard for coating for the drywall is produced in the mechanical fabric using raw material recirculated or 100% recycled. The initial retention / draining program consists of a flocculant fed to the premam or premalla, a coagulant and alum fed on the side or suction part of the ventilation pump and a microparticle fed to the postmam or postamix. This is the pre-test column shown in Table 1 above. The test consists of changing the feeding point of the flocculant from the pre-mesh or pre-fetlock (complete or unmixed raw material including long fiber) to the white water silo (only fine particles). This configuration is indicated as "During the test" in Table 1 above. This change in feed point results in increased drainage as measured by Canadian standard freeness (CSF), increased first step retention (RPP), increased sheet resistance in the machine direction and improved formation.

EXAMPLE 4 The retention / draining program of the invention is incorporated in a worm gear machine of the head box which produces unbleached virgin or pure kraft coated paperboard. It was found that feeding the double polymer retention program that had been in use in the machine for the production of pulp in the belt or metal worm (only fine particles) is increased from 850 to over 900 tons per day. Significantly, a 2% reduction in raw material of the white top separator was realized as a result of improved retention of the unbleached kraft fine particles, brown, gained by the change in feed points. The changes can be made in the composition, operation and arrangement of the method of the present invention described herein without departing from the concept and scope of the invention as defined in the following claims.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property

Claims (14)

1. A method for manufacturing paperboard using a papermaking machine in which the material is fed into an upper box of the papermaking machine to form the paperboard, the method is characterized in that it comprises the steps of: mixing fine particles of water pulp pouring the material with a retention aid to form flocs; feeding the flocs to the upper stream of the long fiber material of the upper box; drain the material to form a sheet; and dry the sheet.

2. A method according to claim 1, characterized in that the retention agent is introduced into the pouring water of the machine.

3. A method according to claim 1, characterized in that at least one flow of the fine pulp is supplied to at least one upper box in a papermaking machine provided with multiple top boxes.

4. A method according to claim 1, characterized in that the retention aid is selected from the group consisting of copolymers of acrylamide with cationic monomers and copolymers of acrylamide with anionic monomers.

5. A method according to claim 1, characterized in that the retention aid is selected from the group consisting of DADMAC, epi-DMA, condensation products of ethylene dichloride and amines, polyethylene imine, modified polyethylene amines and polyamide amines.

6. A method according to claim 5, characterized in that the retention adjuvant used in conjunction with one or more flocculants.

7. A method according to claim 1, characterized in that the retention aid is selected from the group consisting of polyacrylamide and polyethylene oxide.

8. A method according to claim 7, characterized in that it further comprises the addition of a phenol formaldehyde resin.

9. A method according to claim 1, characterized in that it also comprises the addition of cationic starch to the material.

10. A method according to claim 1, characterized in that the retention aid is selected from the group consisting of polyamide, polyamidamine condensate, cationic polystyrene latex, alum, polyaluminum chloride and sodium aluminate.

11. A method in accordance with the claim I, characterized in that it also comprises the addition of a microparticle to the material.

12. A method in accordance with the claim II, characterized in that the microparticle is selected from the group consisting of colloidal silica, bentonite, other smectite clays and anionic latex polymers.

13. A method according to claim 1, characterized in that the retention aid is selected from the group consisting of starch / anionic polyacrylamide / cationic polyacrylamide, colloidal silica / anionic polymer / cationic polymer and bentonite / anionic polymer / cationic polymer.

14. A method according to claim 1, characterized in that the retention aid is added to a point selected from the group consisting of a tray, pouring water and branch or suction side of the ventilation pump.